JSON Formatter & Validator

What is the JSON Formatter & Validator?

JSON (JavaScript Object Notation) is the default data format of web APIs, configuration files and log pipelines. It is easy for machines to parse but painful for humans when it arrives as one long line. A JSON formatter parses the text and prints it again with consistent indentation so nested objects and arrays become readable at a glance.

The same tool doubles as a validator. JSON is stricter than JavaScript object literals: keys must be double-quoted strings, trailing commas are not allowed, comments are not part of the specification, and only true, false and null are valid literals. When the parser fails, the formatter reports the position of the problem so you can fix it quickly.

When to use the JSON Formatter & Validator

Reach for a JSON formatter whenever you debug an API integration: paste the raw response from your network tab, curl output or a log line and read the structure instead of squinting at a single line. It is equally useful before committing configuration files, when you want a consistent style across a team, and when you need to prove to a colleague that a payload is valid. Many developers also keep it open while writing OpenAPI examples, mocking test fixtures and comparing two versions of a response to see which field changed. If the formatter reports an error, fix it at the reported position first, because later errors are often caused by the first one.

How to use the JSON Formatter & Validator

1. Paste your JSON into the input panel, or type it directly.
2. Choose an indentation of 2 spaces, 4 spaces or a tab.
3. Press Format to beautify, or Minify to strip all optional whitespace.
4. If the JSON is invalid, read the error message and jump to the reported line and column.
5. Copy the result to the clipboard or download it as a .json file.

Examples

Minified input:

{"user":{"id":42,"name":"Ada","roles":["admin","editor"]},"active":true}

Formatted with 2-space indentation:

{
  "user": {
    "id": 42,
    "name": "Ada",
    "roles": [
      "admin",
      "editor"
    ]
  },
  "active": true
}

An invalid document and the typical message:

{"name": "Ada",}
// Unexpected token } in JSON at position 16

Common errors and tips

• Trailing commas after the last item are the most common cause of invalid JSON.
• Single quotes are not valid; strings and keys must use double quotes.
• Unescaped characters such as raw newlines or tabs inside a string must be written as \n or \t.
• Large numbers beyond 2⁵³ lose precision in JavaScript parsers; transmit them as strings when exact values matter.
• Sorting keys alphabetically makes diffs between two JSON documents much easier to review.

Privacy: runs entirely in your browser

Your JSON is parsed by JavaScript in the current tab, so API responses containing tokens or personal data never leave your device. This tool runs entirely in your browser: nothing you enter is uploaded, stored or logged on our servers, and it keeps working even if you go offline after the page has loaded.